In his first novel, “For Us, The Living”, discovered and published posthumously, Heinlein proposes an interesting approach to war by inventing a future constitutional amendment that declares, in effect:

Except in case of invasion of the United States, Congress shall not have the power to declare war without submitting the matter to a referendum.

As a novel, “For Us, The Living” is….really bad. (There’s a good reason Heinlein never published it!) The idea of declaring war only by referendum intrigued me, though.

Let’s use Iraq as an example. In Heinlein’s future, the authority to invade Iraq would have been put to public referendum. Only those eligible for military duty vote on war. Those who voted for the war would be the first group drafted, if the referendum passed, and would report for duty immediately. Those who did not vote would be the second group drafted, if needed. Those who voted against the war would be the last group drafted, if needed.

I disagree with his notion that those already serving in the military would not be permitted to vote, but otherwise, I think it would be an interesting experiment.